Various implantable medical devices are advantageously inserted within various body vessels, for example to improve or replace the function of native valves therein. For example, native valves within the heart and veins function to regulate blood flow within the body. Heart valves positioned within the heart direct the flow of blood to and from other organs and pump oxygenated blood to the rest of the body. Venous valves are typically bicuspid valves positioned at varying intervals within veins to permit substantially unidirectional blood to flow toward the heart.
Minimally invasive techniques and instruments for placement of intraluminal medical devices have been developed to treat and repair undesirable conditions within body vessels, including treatment of conditions that affect blood flow such as venous valve insufficiency. Various percutaneous methods of implanting medical devices within the body using intraluminal transcatheter delivery systems can be used to treat a variety of conditions. One or more intraluminal medical devices can be introduced to a point of treatment within a body vessel using a delivery catheter device passed through the vasculature communicating between a remote introductory location and the implantation site, and released from the delivery catheter device at the point of treatment within the body vessel. Intraluminal medical devices can be deployed in a body vessel at a point of treatment and the delivery device subsequently withdrawn from the vessel, while the medical device retained within the vessel to provide sustained improvement in vascular valve function or to increase vessel patency.
Various types of medical devices are advantageously implanted within the body, such as within a blood vessel or within the heart, to treat a variety of conditions. One type of implantable medical device is an endovascular prosthesis that is used to strengthen a blood vessel wall in the location of an aneurysm, or to open an occlusion in a blood vessel. Another common type of medical device is a prosthetic valve. Valves have been implanted in and near the heart and at various positions within the venous system using catheter-based delivery techniques, including the implantation of prosthetic venous valves in the femoral and popliteal veins. Prosthetic valves can also be implanted in various body passages to replace natural valves that are defective or diseased. Prosthetic cardiac valves have been used to replace the native cardiac valves within the heart using percutaneous approaches. Prosthetic valves have also been implanted in veins to promote the flow of blood back to the heart. Blood pressure, as provided by heart activity via the arteries, is normally sufficient to maintain the flow of blood in one direction. The blood pressure in the veins can be much lower than in the arteries principally due to their distance from the heart. Venous valves function to limit the backflow of blood through the veins. Numerous such venous valves are located throughout the venous system and are particularly important to maintaining proper blood flow in the lower extremities. Venous valves can become incompetent and lead to chronic venous insufficiency. Various techniques have been developed for treating incompetent venous valves including valvuloplasty, transplantation, and replacement with a prosthetic valve. These techniques include both open and percutaneous approaches.
Inhibiting or preventing thrombosis and platelet deposition on an implantable device within the body is important in promoting continued function of the medical device within the body, particularly within blood vessels. Post-implantation thrombosis and platelet deposition on surfaces of implantable medical devices prosthesis undesirably reduce the patency rate of many implantable medical devices. For example, thrombosis and platelet deposition within an endovascular prosthesis may occlude the conduit defined by the endovascular prosthesis or compromise the function of an implanted valve by limiting the motion or responsiveness of moveable portions of the device such as valve leaflets. Many factors contribute to thrombosis and platelet deposition on the surfaces of implanted prosthesis. The properties of the material or materials forming the endovascular prosthesis are believed to be one important factor that can contribute to the likelihood of undesirable levels of post-implantation thrombus formation or platelet deposition on the implanted device. The formation of blood clots, or thrombus, on the surface of an endovascular prosthesis can both degrade the intended performance of the prosthesis and even undesirably restrict or occlude desirable fluid flow within a body vessel.
What is needed are implantable medical devices configured to mitigate or prevent thrombosis or promote the remodeling of portions of the device within a body vessel. The implantable medical devices provided herein are configured to provide implantable medical devices suitable for percutaneously delivery, such as venous valves or heart valves, that include a remodelable material and can be delivered using a minimally invasive catheter-based delivery system.